You want a laptop that handles heavy work and gaming without stuttering. Buy one with specs that exceed your current needs so you aren't shopping again in two years.
Wait for the back-to-school season when manufacturers push new inventory. This is usually when last year's models drop in price, giving you more power for your dollar.
The 0% intro APR is a deadline, not free money. If you still have a balance after 15 months, the bank will start charging interest on whatever is left, which gets expensive fast.